Akihide Hibara

We have fabricated nanometer-sized channels, demonstrated a technique for the introduction of liquid into the channels, and carried out time-resolved fluorescence measurements of aqueous solutions. In this study, 330-nm- and 850-nm-sized channels were fabricated on fused-silica substrates by fast atom beam etching and hydrofluoric acid bonding methods. A liquid introduction method utilizing capillary action was demonstrated. The liquid introduction was observed under an optical microscope, and t

A capillarity restricted modification method for microchannel surfaces was developed for gas--liquid microchemical operations in microchips. In this method, a microstructure combining shallow and deep microchannels and the principle of capillarity were utilized for chemical modification of a restricted area of a microchannel. A hydrophobic--hydrophilic patterning in microchannels was prepared as an example for guiding gas and liquid flows along the respective microchannels. Validity of the patte

We demonstrated a liquid/liquid and a gas/liquid two-phase crossing flow in glass microchips. A 250-microm-wide microchannel for aqueous-phase flow was fabricated on a top glass plate. Then, as a way to utilize the surface energy difference for stable phase confluence and separation, a 250-microm-wide microchannel for organic-phase (or gas-phase) flow was fabricated on a bottom glass plate and the wall was chemically modified by octadecylsilane (ODS) group. The top and bottom plates were sealed

Microscopic quasi-elastic laser scattering (muQELS) spectroscopy has been developed for analysis of interfacial phenomena at laminar multiphase microflow in a microchannel. Transport phenomena of a metal chelate through a water/toluene interface were measured, and transient adsorption of the chelate in the initial step of the transport was measured. A water/methanol miscible interface was also measured, and the interfacial free energy of a miscible interface was determined for the first time. Th

Abstract This paper reports a novel distillation method in microchannels. For the gas–liquid separator in the evaporator, hydrophilic–hydrophobic patterned microchannel structure was utilized. In order to control condensation of the vapor, nanopillar structures having a capillary radius of 270 nm were fabricated after the separator. In the nanopillars, vapor pressure is lower than that at a flat liquid surface. An aqueous solution of 9.0 wt % ethanol was used as a model sample, and concentration

We report a contactless surface tension measurement method of micrometer-sized aerosol droplets. In this method, we assume spherical spontaneous resonance of a thermally induced capillary wave. First, an aerosol droplet with a radius ranging from 4.7 to 12.4 μm is trapped by means of a simple single-beam optical trapping configuration, and the frequency shift power spectrum of the light passing the droplet is measured. The spectrum in each case exhibits several peaks in a frequency range of seve